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A8 Overheated, Exp Tank Hissing, Air-Con

barry1394 Jul 16, 2009

  1. barry1394

    barry1394 New Member

    Hi folks,

    My A8 just overheated, managed to get it to the garage. They replaced the thermostat and the water pump. So far so good - all working again.

    Today I noticed the expansion tank is hissing after a run.

    Prior to the overheat incident I could hear a lot of water sloshing about in the air-con outlets. I manged to pump out about 2 pints of water from the rear seat vent!

    The water in the air-con is more like rain water - no anti-freeze or grubby water, all clean.

    I am most concerned about the expansion tank problem.

    Any of this make any sense?

  2. A8_Tony

    A8_Tony Member

    Hi Barry,

    What model '8 do you have? If you have a D2 there's something lovingly referred to as 'Botangs Hole' which can be accessed via the wheelarch which, when blocked, will cause copious amounts of water to enter the cabin. This may be your problem.

    As for the expansion tank, check your hoses. It sounds like the hot air is being blown out of a leak, and therefore causing your hissing sound.

    Welcome to the forum BTW, don't forget to check out the A8 Owners Club as there are some great benefits to be had (including discounts on mechanical work/spares) :thumbsup:
  3. barry1394

    barry1394 New Member

    Hi Tony,

    Yes, I think it is a D2. Have sorted the hissing. It was pressure being equalised after the engine goes off. Guy at the garage has an A4 it his does it too. That's a relief.

    Those pipes under the wheel arch, I believe I've checked those. They seem OK.

    Have just had a lot of rain here and it now sounds like I must have about a gallon of water in the air-con system! Movement of the car sends it all over the inside of the vents. When the fan is on full I can see water coming out the front and rear vents.

    I just don't know how it is getting in. Can anyone advise?

  4. bigjizzy

    bigjizzy New Member

    Hi mate,

    i have had similar issues.

    The water behind the Dash is in the Air con reservoir. It holds the condensation from the air con.

    Normally it leaks out through an orange pipe behind the dash, and goes under the car.

    This needs blowing out and all your problems will be solved.

    Incidentally the hissing confused me as well :) :)

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